• Journal of the Society of Disaster Information
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• v.19 no.1
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• pp.173-183
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• 2023

Purpose: In order to reduce industrial accidents caused by forklift trucks, it is actually necessary to analyze the causes of accidents. This study aims to present disaster prevention measures by analyzing accident cases by forklift accident type. Method: For the analysis of industrial accidents, including serious industrial accidents caused by forklifts from 2021 to 2022, accident statistics from the Korea Occupational Safety and Health Agency were used to analyze accidents in four types. Result: In the last two years, the total number of victims, including deaths and other serious injuries, was 2,559, which was 1,396 in 2021 and 1,163 in 2022. Disaster prevention measures were presented for industrial accidents by size and occurrence type of equipment that cause serious industrial accidents in which more than 1,000 people are injured annually. Conclusion: It is necessary to expand the number of workers subject to the forklift financial support project to less than 100. It is necessary to amend the proviso on boarding restrictions in Article 86, Paragraph 7 of the ｢Regulations on Industrial Safety and Health Standards｣. It is mandatory to install front and rear cameras. It is necessary to install driving-linked safety belts. It is necessary to install line beams obligatory. It is necessary to expand the subject of forklift special safety and health education to workplaces that have more than one forklift truck, and it is necessary to redesignate the training hours to 16 hours every year.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.219-225
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• 2007

컴퓨터교과는 학생들의 일반적인 학업성취 개인차 요인과 더불어 필수 교과가 아니기 때문에 학교 혹은 교사마다 교육하는 내용이 상이하여 학생들이 상급학교로 진학하였을 때 학생들 간의 수준 차가 심화된다. 이러한 다양한 수준차가 있는 학생들을 교사 1인이 한정된 시간 안에 모든 학생들의 수준에 맞추어 지도하는 것은 대단히 어렵다. 또 넓은 컴퓨터실에서는 학생들의 주위가 분산될 우려가 많으므로 학생들의 행동을 수시로 관리할 필요가 있다. 이러한 컴퓨터교과 실습수업 시에는 보다 효과적인 지도방법이 요구된다. 이에 본 연구에서는 컴퓨터교과 실습지도 방법의 장단점을 분석하고, 컴퓨터교과 실습수업 시 널리 사용되는 시범 실습법의 단점을 보완할 수 있는 도우미학생 활용 시범 실습법을 제안하고, 중학교 컴퓨터 정규교과 시간에 적용하여 그 효과를 검증하였다. 도우미학생 활용 시범 실습법이란 교사는 실습내용을 설명하고, 모든 학생들은 교사의 설명과 동시에 실습을 하며, 도우미학생의 실습내용이 빔 프로젝트를 통해 다른 학생들에게 보여짐으로써 교사의 시범을 대신하는 방법을 말한다. 컴퓨터교과는 설명만으로도 실습 가능한 내용이 많아 이러한 지도방법이 가능하다 이 방법은 실습내용을 최소한의 작은 단계로 구분하고, 각 단계별로 교사의 설명과 개별지도, 모든 학생의 실습과 관찰이 동시에 이루어진다. 이 방법은 교사의 행동이 자유로워 설명과 동시에 개별지도가 가능해 개별지도의 확대를 가져올 수 있으며, 학생들에게 보다 많은 즉각적인 피드백을 줄 수 있으며, 학생들의 행동을 수시로 관리할 수 있다는 장점이 있다. 또한 본 연구에서는 검증도구로 'html 태그' 단원 5차시 분량의 과제수행능력평가도구를 개발하여 사용하였다. 검증결과 학업성취 중하수준의 도우미학생 활용 시범 실습으로 수업한 집단은 통제반과 유의미한 차이가 없었으나, 학업성취 중상수준의 도우미학생 활용 시범실습으로 수업한 집단은 통제반에 비해 과제수행능력에 있어서 유의미한 차이를 보였다 이로써 제안한 지도방법의 효과성을 입증하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1719-1730
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• 2013

Recently BIM technology has been expanded for using in construction project. However its spread has been delayed than the initial expectations, due to the high-cost of BIM infrastructure development, the lack of regulations, the lack of process and so forth. Therefore, this research proposes the cloud computing based BIM service for saving the cost of BIM infrastructure development and providing various BIM Services to meet the domestic process. In order to achieve this, we perform a survey on the cloud computing based BIM service and develope the prototype system as the core technology of proposed service. The developed the prototype system consists of the IFC based BIM server for IaaS (Infrastructure as a Service) and the viewer for SaaS (Software as a Service). This research also conducts the performance test for their applicability and verifies that the results of this research can be used as core components in the cloud computing based BIM service.

• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.295-301
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• 2018

Recently, GPS(Global Positioning System) array antenna technology is generally used and widely adopted as a national infrastructure structure and aero-vehicles for protection the GPS signal reception. Until now, the 2-dimensional planar array is universally used for its applications in the array antenna signal processing, however relatively higher altitude air vehicles such as UAV experiences additional null zones induced by low altitude GPS interferences which is located in a symmetry zone of antenna horizontal plane and this could make the receiving antenna pattern coverage reduction. In this paper, we improved 20% of the beam pattern receiving performance and 13 dB correlation value improvement by eliminating the interference mirror images.

• Archives of design research
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• v.19 no.1 s.63
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• pp.253-262
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• 2006

Research of color has been developed and also has raised consumer desire through changing from a tool to pursue curiosity or beauty to a tool creating effects in the 20th century. People have been interested in colors as a dynamic expression of results since the color TV appeared. The meaning of colors has been recently diversified as the roles of colors became important to the emotional aspects of design. While auto colors have developed along with such changes of the times, black led the color trend during the first half of the 20th century from 1900 to 1950, a transitional period of economic growth and world war. Since then, automobile production has increased apace with the rapid economic growth throughout the world and automobiles became the most expensive item out of the goods that people use. Accordingly, increasing production induced facility investment in mass production and a technology leveling was achieved. Auto manufacturing processes are very complicated, auto makers gradually recognized that software changes such as to colors or materials was an easier way for the improvement of brand identity as opposed to hardware changes such as the mechanical or design components of the body. Color planning and development systems were segmented in various aspects. In the segmentation issue, pigment technology and painting methods are important elements that have an influence on body colors and have a higher technical correlation with colors than in other industries. In other words, the advanced mixture of pigments is creating new body colors that have not existed previously. This diversifies the painting structure and methods and so maximizes the transparency and depth of body colors. Thus, body colors that are closely related to technical factors will increase in the future and research on color preferences by region have been systemized to cope with global competition due to the expansion and change of auto export regions.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.185-194
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• 1998

Flow-induced voids during resin impregnation and poor fiber wetting give serious effects on the mechanical properties of composites in resin transfer molding process. In order to better understand the characteristics of resin flow and to investigate the mechanism of void formation, flow visualization experiment for the resin impregnation was carried out on plain weaving glass fiber mats using silicon oils with various viscosity values. The permeability and the capillary pressure for the fiber mats of different porosities were obtained by measuring the penetration length of the resin with time and with various injection pressure. At low porosity and low operating pressure, the capillary pressure played a significant role in impregnation process. Video-assisted microscopy was used in taking the magnified photograph of the flow front of the resin to investigate the effect of the capillary pressure on the void formation. The results showed that the voids were formed easily when the capillary pressure was relatively high. No voids were detected above the critical capillary number of 2.75$\times$$10^{-3}, and below the critical number the void content increased exponentially with decrease of the capillary number. The content of void formed was independent of the viscosity of the resin. For a given capillary number, the void content reduced with the lower porosity of the fiber mat.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.416-417
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• 2013

최근 질화물계 발광다이오드(light emitting diode, LED) 소자는 핸드폰, 스마트 TV 등의 디스플레이 분야와 실내외조명, 감성조명, 특수조명 등의 조명분야에 그 응용분야가 급속히 확대되고 있다. 이러한 LED 소자는 에너지 절감과 친환경에 장점을 가지고, 가까운 미래에 조명시장을 대체할 것으로 예상된다. 이를 만족하기 위해서는 현재보다 더 높은 효율을 갖는 LED 개발이 요구되어지고 있는 상황이다. 일반적으로 질화물계 LED 소자의 효율은 내부양자 효율, 광추출 효율 등으로 나타낼 수 있다. 내부 양자효율은 성장된 결정의 질의 개선 및 다층의 이종접합 또는 다중양자우물 구조와 같이 활성층의 캐리어 농도를 높이는 접합구조로 설계되어 80% 이상의 효율을 나타낸다. 그러나 광추출 효율은 이에 미치지 못하고 있다. 이는 반도체 재료의 높은 굴절률로 인하여 빛이 외부로 탈출하지 못하고 내부로 반사되거나 물질 안에서 흡수가 일어나기 때문이다. 따라서 이러한 문제를 해결하기 위해 많은 연구 그룹들은, 표면에 패턴 형성하여 빛의 전반사를 줄여 그 효율을 올리는 연구결과를 보고하고 있다. 대표적인 방법으로는 wet etching, 전자빔 리소그라피, 나노임프린트 리소그라피, 레이저 홀로 리그라피, 나노스피어 리소그라피 등이 사용되고 있다. 이 중, 나노스피어 리소그라피는 폴리스틸렌 혹은 실리카 등과 같은 나노 크기의 bead를 사용하여 반도체 기판 표면에 단일층으로 고르게 코팅한 마스크로 사용하여 패턴을 주는 방법이다. 이 방법의 장점으로는 대면적에 균일한 패턴을 형성할 수 있고, 공정비용이 저렴하여 양산하기에 적합하다는 특징이 있다. 나노스피어 리소그라피를 통해서 표면에 생성된 패턴 모양의 각도에 따라서, 식각되는 깊이에 변화에 따라 실험한 결과들은 있지만, 아직까지 크기가 다른 나노입자들의 마스크 이용하여 형성된 패턴 밀도에 따른 광 추출 효과에 대한 연구가 많이 미흡하다. 따라서 본 연구에서는 다양한 크기의 실리카로 패턴을 형성시켜 패턴 밀도에 대한 광추출 효율의 효과에 대해서 조사하였다. 실험 방법으론, DI, 에탄올, TEOS, 암모니아의 순서대로 그 혼합 비율을 조정하여 100, 250, 500 nm 크기의 나노입자를 합성하였고 이것을 질화물계 LED의 표면 위에 단일층으로 스핀코팅 방법을 통해 코팅을 하였다. 그 후 ICP-RIE 방법으로 필라 패턴을 형성하였는데, 그 결과 100 nm SiO2 입자를 이용한 경우 $4.5{\times}10^9$/$cm^2$, 250 nm의 경우 $1.4{\times}10^9$/$cm^2$, 500 nm의 경우 $0.4{\times}10^9$/$cm^2$의 패턴의 밀도를 보여주었다(Fig. 1). 패턴의 밀도에 따라 전계광학적 특성을 확인하여 보았는데, 그 결과는 평평한 표면과 비교하였을 때 100 nm에서 383%, 250 nm에서는 320%, 500 nm에서는 244% 상승하는 결과를 보여주었다(Fig. 2). 이번 실험을 통해서 LED의 광추출 효율은 표면 모양과 깊이 뿐 아니라 밀도가 커질수록 그 효율이 올라간다는 사실을 알 수 있었다.

• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.127-131
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• 2008

A refractometric glucose biosensor incorporating a vertically coupled microring resonator in polymers was proposed and realized. The ring was covered with a target analyte of glucose solution with a certain concentration, so that its effective refractive index could be altered and, as a result, the resonance wavelength of the sensor was shifted. Therefore the concentration of the glucose solution can be estimated by observing the shift in the resonance wavelength. Two schemes were exploited for enhancing the sensitivity of the sensor. First, the effective refractive index of the polymeric waveguide used for the resonator sensor was adjusted to approach that of the target analyte as best as possible. Second, the ring waveguide, which serves as a crucial sensing part, was appropriately over-etched to enlarge its contact area with the analyte. The proposed resonator sensor was designed with the beam propagation method. The refractive indices of the core and cladding polymer involved were 1.430 and 1.375 respectively, leading to the waveguide's effective refractive index of ${\sim}1.390$, which is faiirly close to that of the glucose solution of ${\sim}1.333$. The prepared ring resonator with the $400-{\mu}m$ radius exhibited the free spectral range of 0.66 nm, the bandwidth of 0.15 nm, and the quality factor of 10,000. For the sensor operating at 1,550 nm wavelength, the achieved sensitivity was as great as 0.28 pm/(mg/dL), which is equivalent to 200 nm/RIU.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.95-103
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• 2009

An efficient symbol time synchronization scheme for IEEE 802.11n MIMO-OFDM based WLAN systems using cyclic shift diversity (CSD) preamble is proposed. CSD is used to prevent unintentional beamforming when the same preamble signal is transmitted through transmit antennas. However, it is difficult to find a proper starting-point of the OFDM symbol with the conventional algorithms because of time offset by multi-peaks which are result from cross-correlation of received CSD preamble with a known short training symbol. In addition, the performance of symbol time sync. is affected by AGC and packet detection position. In this paper, an optimal symbol time synch. algorithm which is composed of the boundary detection scheme between LTS and OFDM symbols, the verification scheme for enhancement of boundary detection accuracy, and the SNR-varying threshold estimation scheme is proposed. Simulation result show that the proposed algorithm has performance gains of 4.3dB in SNR compared to the conventional algorithms at the rate of 1% sync. failure probability for $2{\times}2$ MIMO-OFDM system and 18dB at 0.1% when maximum frequency offset exists. It also can be applied to $4{\times}4$ MIMO-OFDM system without any modification. Hence, it is very suitable for MIMO-OFDM WLAN systems using CSD preamble.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.250-253
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• 2002

The post harvest treatment of barley had many hard work steps, such as drying, cleaning, and packing. This is a reason why farmer doesn't like to cultivate barley. This study was conducted to investigate the optimum post harvest management of bulk-harvested barley using rice processing complex (RPC). Bulk-harvested barley was stored to 61.1% after 6pm at RPC. Grain moisture contents of bulk-harvested barley differed from storing date, farmer household, and field. Required dry hours were different with grain moistures contents. The average dry hour was 9.5 hours per 10a and dry rate was 0.89%. The proportion of impurity removed by coarse cleaning differed from grain moisture contents, as higher grain moisture content made impurity rate increase up to 38.9%. Cost of drying of bulk-harvested barley was 50won per ㎏ at above 24% of grain moisture contents, and the average dry cost was 41.25 won/㎏ and 14,400won/10a. The 62% of barley treated was stored in indoor-grain bin, and the others packed in 500 ㎏-poly con bag were stored in warehouse insulated.